Changing Climate In Argentina Is Killing Penguin ChicksThe world's largest breeding colony of Magellanic penguins is seeing unprecedented deaths among young birds. A scientist who has spent 30 years studying the penguins says that climate change is to blame — triggering, among other things, more heat waves and wetter storms that kill fledglings.

Magellanic penguins strut their stuff on the rocky shoreline of Argentina's Punta Tombo, home to the largest colony of the birds in the world.
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There's a patch of seashore along the coast of Argentina where hundreds of thousands of penguins make their home. It's called Punta Tombo. Dee Boersma, a conservation biologist at the University of Washington, has been going there for 30 years, and she's discovered that a changing climate is killing those penguins.

I visited Boersma in 2003 for NPR's Radio Expeditions program. She literally lived amid the colony, the world's largest group of Magellanic penguins. Even then, she was worried. Penguin numbers had been dropping, as much as 20 percent below their original population.

You wouldn't have known it though on the beach at Punta Tombo. Once you walked over the big dune just back of the beach, it was all penguins — screeching, honking, strutting and braying, the last being the reason they're also called jackass penguins. When it comes to noisemaking, these 2-footers punch above their weight.

Nearby was a ragged-looking double-wide trailer — at the time, Boersma's temporary home away from the University of Washington. "We get to live really close to the penguins," she said, bending down to look under the trailer. "See right here underneath the trailer." It was a penguin looking up at us.

"Last night there were fights underneath the trailers," Boersma said. The only thing that drowned out the squawking was the 30-knot wind that blows there most of the time — hard enough to make the trailer rock back and forth most of the night.

That was Boersma's 20th year at Punta Tombo. "One of the things that I certainly didn't anticipate when I started this," she said, "is that these penguins could tell us as much as I think they are ... about the environment."

What they were saying was: Things weren't going well. The colony had shrunk and Boersma didn't know why, though electronic tags she'd put on some of the penguins told her they were swimming farther than normal to find food.

She thought maybe changes in the environment brought about by climate change were pushing the squid that penguins eat farther out to sea. The sea surface temperature of the Atlantic had gone up over the past few decades. Potentially, that changes not only currents but also weather patterns.

It wasn't until around 2010 that Boersma figured out the real problem: Punta Tombo was experiencing bigger, stronger and wetter rainstorms. "When you get three years in a row where lots of chicks die because they get wet, it hits you pretty hard," she says now.

Now, you might be wondering: Penguins swim. They love the water. They live in cold places, like the Antarctic. And now they're dying of hypothermia after a heavy rain? How can that be?

"You have to really know penguins to understand why," says Boersma. "Chicks are covered in down. Their juvenile plumage ... doesn't even really come in to protect them at all until they are older than 40 days. So until they get some of their juvenile plumage, they're not waterproof — at all."

And local weather records show that things had been changing for years. "There's more rainfall," Boersma says, "and more of these severe storms and that's what can kill penguin chicks — if the storm comes when they are more vulnerable."

And they are more vulnerable. Here's why: Usually, the penguins hatch their young at the same time, over the course of about two weeks in December. But now, for some reason that still eludes Boersma, the birds are hatching over a six-week period. So the period of time when chicks are vulnerable to storms has stretched out.

Moreover, the hatch is now taking place later in the year — at a time when there are more storms in Patagonia.

Though quiet here, Magellanic penguins are widely known as "jackass penguins" for their honking and braying.
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The penguins are struggling with this new climate. In one year, half the hatchlings died in storms. On a few occasions, chicks have also died from heat waves. As Boersma points out, even as storms are getting bigger and more frequent, summertime heat waves are more common too. She notes that these effects are predicted by climate scientists. Warmer air temperatures mean not only hotter weather but more evaporation from the Atlantic, which puts more moisture in the air and thus creates wetter storms. "It's these climate change events that penguins didn't have in the past," says Boersma, with an urgency born of living with these creatures for almost half her life. "And it's not like penguins can adapt."

Boersma got research funding from the Wildlife Conservation Society. The society's South American expert, biologist Martin Mendez, says when things go wrong with wildlife, it's hard to track down the cause. There are so many potential culprits.

"It is sometimes difficult to stay every year for a decade or two," Mendez says. "But this shows you the value of being on the ground for a long time, especially if it relates to climate change."

Boersma has 30 years of data on her colony. Mendez says one other project in the region has that kind of history, in the Patagonia Mountains. There's less rainfall, on average, in the mountains now. And that's changing the higher elevation lakes, where Argentina's flamingos live. "And less water," says Mendez, means the lakes "become more salty and more unsuitable for flamingos." Essentially, for wildlife, a changing climate is a crapshoot.

Boersma published her findings this week in the journal PLoS One. She's planning more visits to Punta Tombo. Now she's got herself a real house to live in there. As for the trailer — it's now on exhibit in a natural history museum just down the road from the colony.

Recordings of the Punta Tombo penguins used in our radio story come from the Radio Expedition archive at the Cornell Lab of Ornithology's Macaulay Library.